Installation

Installing via PXE works well. It requires another computer to use as PXE host, and some configuration.

Kernel

Append acpi_osi=Linux to your /boot/grub/menu.lst to set the EeePC ACPI Interfaces to "Linux-Mode". Then the current kernel (as of writing 2.6.34) will autoload the eeepc_laptop module and everything works perfectly.
Eg.

Xorg

Video Driver

Device Autodetection

Everything works out of the box. xf86-input-evdev gets installed automatically with the xorg package. The current Xorg does not depend on HAL anymore, it uses dbus directly.

DPI setting

A good comfortable setting would be 96dpi or 75dpi if you like your fonts really small. An easy way to set your DPI would be to add this to the end of /etc/X11/xinit/xserverrc:

exec /usr/bin/X -nolisten tcp -dpi 96

(-nolisten is also a good idea for reducing unneeded system activity)

Graphic Performance

The default graphic performance is the best you can currently get. It is not needed to add "optimizations" like "AccelMethod" "exa" to your xorg.conf, because these will get ignored by the current version of the Intel drivers anyway. The only thing you can add is XvMC Hardware decoding support, which allows your Intel graphics adapter to decode MPEG2 video material. To do this and set XvMC, here is a minimal xorg.conf:

Powersaving and ACPI

Your best bet is to disable all hardware you do not intend to use (to access the BIOS settings, press F2 after rebooting).

laptop-mode-tools

Laptop-mode-tools provides an easy way to setup most of the available power saving options, which include spinning down the hard drive and adjusting the power saving modes of the harddrive and CPU, as well as autosuspending the USB-ports, setting screen brightness, configuring the eee's own 'Super Hybrid Engine', etc.

Setup

# pacman -S laptop-mode-tools

The main configuration file is /etc/laptop-mode/laptop-mode.conf, plus there are several separate configuration files in /etc/laptop-mode/conf.d/ for the various power saving modules managed by laptop-mode-tools. The files are well commented, so it should be easy to set everything up as needed. (For more information, see Laptop Mode Tools)

To make the daemon start at boot, add laptop-mode to the DAEMONS array in /etc/rc.conf.

LCD brightness

The relevant configuration file is /etc/laptop-mode/conf.d/lcd-brightness.conf. Brightness values are between 0 (darkest) and 15 (brightest). An example of usable settings:

This functionality requires the package cpufrequtils. The package also provides a daemon which can be used on its own (See CPU Frequency Scaling for its usage). If handling frequency scaling through laptop-mode-tools, the cpufreq daemon should not be loaded, and its configuration file options can remain commented out, since the settings will come from /etc/laptop-mode/conf.d/cpufreq.conf.

Either way, cpufreq requires the kernel module acpi-cpufreq.

SHE

The eeepc's 'Super Hybrid Engine' has a significant effect on powersaving. This underclocks the FSB for powersave/overclocks for performance and can be controlled via the file /sys/devices/platform/eeepc/cpufv which is provided by the module eeepc_laptop.
You can manage this with laptop-mode-tools. The relevant config file is /etc/laptop-mode/conf.d/eee-superhe.conf.

USB suspend

Config file: /etc/laptop-mode/conf.d/usb-autosuspend.conf

Tip: make use of the option to disable the suspending of some USB hardware (eg. 3g modems) by using lsusb to get the ID and then insert it in the configuration file.

Audio power save

"With the automatic power-saving, the driver turns off the codec power appropriately when no operation is required. When no applications use the device and/or no analog loopback is set, the power disablement is done fully or partially. It'll save a certain power consumption, thus good for laptops (even for desktops)." — Kernel documentation

To make this change permanent, you need add the next line to /etc/modprobe.d/modprobe.conf